1. Field of the Invention
The invention relates generally to the field of communications and also and more particularly to communication systems including portable, hand-held transceiver terminals.
2. Description of the Related Art
In the past, users of computer-supported data processing systems typically were restrained by limited availability or a lack of devices for conveniently interacting with existing computer systems. During changes from existing bookkeeping or accounting systems to computer systems to existing bookkeeping or accounting systems procedural changes were typically minimized. Consequently, conventional data entry procedures usually remained in effect. Adherence to existing procedures with the concurrent use of computer systems did in many instances impede the effective implementation of computer systems. For example, in commercial activities which traditionally relied on written logs or records, the practice of making written records and transcribing the records to electronic, computer-maintained data bases typically continued without recognition that an unnecessary duplication of efforts was involved. The duplication occurred by initially generating written records as it had been done in the past, and then transcribing the written records to electronic data bases. Efforts to make computers more accessible have in the more recent past resulted in the development of portable data terminals which interface with computers.
Two types of portable data terminals have found considerable use in commercial systems relating to merchandise delivery, warehousing and inventory keeping systems. Both types of data terminals are portable. They characteristically include portable power sources of sufficient storage capacity to power the respective terminals over the entire length of contemplated working periods. The working periods may constitute the length of a normal working day or an even longer period.
A first type of data terminal is found to be particularly adaptable to the generation of delivery records or customer invoices, such as those typically generated in delivery route operations. A strength or desirable feature of the first type of terminal is that it is self-contained. A delivery route driver typically carries the terminal with him on the delivery route, such route could conceivably include many stops. The stops may be planned to be made in predetermined order, or at other times they may be chosen at random. Variable modes of usage and application need to be served by terminal-resident recording and processing circuits. Because of the self-contained mode of operation of the first type data terminal, typically, a substantial portion of available housing space is taken up with memory boards. Memory space is needed in form of random access memory circuits for storing data, and also as preprogrammed circuits for routine functions which minimize the work effort by a driver or delivery man and make the terminal a time saver. Data stored in such first type of terminal are typically transferred or "down loaded" to a central computer in a batch transaction after the delivery trip has been completed.
The second type of portable terminal is adapted for use in warehouses or in merchandizing establishments to generate, for example, real time inventory records. In distinction over the first type of terminal, usage requirements of the second type of terminal typically involve handling or recording an even greater number of data, typically relating to merchandise items. Also in contrast to the first type of terminal, the need for mobility of the second type terminal differs by nature of the application. Typically, the second type terminal needs to be fully operational only within the confines of a designated, restricted area, such as a stockroom of a merchandise building, or within a somewhat larger area of a warehouse. In such a relatively restricted space, a data terminal is ideally equipped with a typical RF transceiver to communicate via a base transceiver station with a central computer.
The second type terminal, instead of having a large electronic memory or a substantial circuit section with pre-programmed functions, consequently need include only a minimum of memory and pre-programmed functions in addition to such a transceiver circuit. Typically a predetermined number of the transceiver-equipped data terminals are coupled by means of a multiplexing scheme through the base transceiver station to the same central computer. A distinct advantage of such RF-coupled communication link is that a comparatively light and small, hand-held terminal possesses a data processing power and data storage capacity which is limited only by the power and capacity of a central computer to which it is communicatively connected. Another advantage of direct, interactive communication between the hand-held terminal and the computer is that data files of the central computer are updated on a real time basis and that each additional terminal coupled to the same central computer has the benefit of the most up-to-date information.
The two types of hand-held data terminals have developed in parallel and are distinct in design in spite of some similarities. One outward and immediately apparent distinction, in many cases, between the two types of data terminals is the presence of antennae on transceiver type of terminals. Until recently, all transceiver type of data terminals have featured such antennae. Only recently some hand held units have been marketed with internally located antennae, such as a hand set of a cordless telephone or a commercial data terminal manufactured by Motorola, for example. Using conventional transceiver type data terminals brings the realization of the inconvenience caused by the presence of the antennae. The extending antennae are easily damaged or broken off. Even flexible type antennae are damaged, when they are accidentally jammed against a wall in a crowded stock room or when they are carelessly used as a carrying handle. In spite of such shortcomings of external antennae, to maintain optimum transmission ranges, the use of external antennae has prevailed in most instances.
Where it does become desirable to eliminate external antennae, and particularly in those applications where the transmission range may not be decreased by relocating the antennae to within the housing of the hand-held terminal, the size of the hand-held terminal is apt to increase accordingly. In short range devices for voice communication, rather than for data communication, such as a handset of a cordless telephone, the use of untuned antennae in the form of a single wire looped within the housing of the handset has been used to eliminate the external antenna without increase of the size of the handset. For interactive data terminals, on the other hand, the use of tuned antennae for accuracy in data transmission becomes desirable. Thus, data terminals in most cases are still using conventional external antennae which may be tuned to optimize their performance.
In addition to the above-mentioned disadvantages of external antennae, the existence of external antennae is an external, physical distinction of the second type of portable terminal with respect to the first type to cause certain undesirable incompatibilities between the two type terminals. It would be desirable, for example, to use the same peripheral devices, such as printers, for both types of terminals. The presence of the antennae typically cause physical interference, particularly when connector cradles are provided to establish the connection to the peripherals. In those instances, the antennae typically interfere with the attachment of such peripheral devices to the terminals. One solution to the latter problem is to provide special connectors to eliminate such interference. This solution is cumbersome and undesirable in most instances.